Transmission



uw, 7, 1956 R. c. HOFFMAN 21,757,557

TRANSMISSION 6 Sheets-Sheet l Filed NOV. 4. 1947 7' 4 Ngs @L PJINVENTOR. 255544@ BY R. C. HOFFMAN TRANSMISSION Aug., 7, 1956 6Sheets-Sheet 2 Filed Nov. 4, 1947 INVENTOR. 2647656' Cf /y/a BY Aug.. Y,w56 R. c. HOFFMAN 2,757,557

TRANSMISSION mm Nov. 4, 1947 e sheds-Sheet s 1N VEN TOR.

Wagens' #aff/afa Aug., 7, 1956 R. c. HOFFMAN TRANSMISSION 6 Sheets-SheetFiled NOV. 4, 1947 army/wwwa,

Aug.. 7, 1956 R. c. HOFFMAN TRANSMISSION 6 Sheets-Sheet 5 Filed Nov. 4.-L94? NWN NNN

QWN

ug. 7, 1956 R. c. HOFFMAN TRANSMISSION 6 Sheets-Sheet 6 Filed Nov. 4.1947 ESN m NWN NMN www RWNN United States Patent O TRANSMISSION RoscoeC. Hoiman, Detroit, Mich. Application November 4, 1947, Serial No.783,930

1 Claim. (Cl. 74-740) The present invention relates to change speed geartransmissions, particularly for automotive vehicles.

An important object of the invention is to provide an improvedautomotive transmission mechanism incorporating both planetary gearingand conventional spur gears controllable by power operable frictionclutches, the arrangement being such as to dispense with the need for amain friction clutch and to provide three or more forward speeds and oneor more suitable reverse speeds, as may be desired in accordance withconsiderations of engineering and design, in a transmission of verysimple, compact and rugged construction, and which is no designed as toinclude only a single planetary gear set, a simple train of spur gears,and two friction clutches.

A further object of the invention is to provide such a transmissionincorporating overrunning clutch-type re action means arranged in animproved and novel manner and functioning under certain conditions toprovide a free wheeling action in reduced speed forward drives, novelmeans being provided for preventing free wheeling action in at least oneof the reduced speed drives despite the presence of the overrunningclutches.

Still another object is to provide such a transmission which is of verysimple, compact and inexpensive con-` struction and which lends itselfwell to automatic control.

Another object is to provide an improved transmission construction ofthe character indicated incorporating a plurality of coaxially disposedpower operated friction clutches for controlling the action of thetransmission and a plurality of tclescoping shafts projecting axiallyfrom and connected to the clutches, a planetary gear set carried uponone of the projecting shafts, spur gear means also mounted coaxiallywith the projecting shafts but drivable through the planetary gear setat any of a plurality of ratios, and a housing having separatecompartments for the clutches and for the gear means, the gear meansincluding a planetary set and spur gear means, both co* axial with thetelescoping projecting shafts above referred to, and additional torquetransmitting and reversing gear means laterally offset from butsubstantially parallel with respect to the planetary gear set and theaforementioned spur gear means,

Another important object of the invention is to provide automaticcontrolling means for a transmission of the indicated character, thecontrolling means being so arranged that when installed in an automotivevehicle in conjunction with such a transmission, automatic gear shiftingis provided whereby changes of driving ratio are eiected withoutrequiring the exercise of skill and judgment on the part of the driver.

A related object is to provide such improved automatically operableratio contro-lling means which is of greatly simplified character and soarranged that there is very little likelihood of the occurrence of anyfailure which would interfere with proper operation of the transmissionin the intended automatic manner, the arrangement being such that thedriver may exercise supervisory rice 2 control at will to alter theautomatic functioning when desired.

Still another object is to provide such an improved automaticallyoperable ratio controlling system incorporating improved and simplifiedkick-down shifting means for reducing the speed ratio of the gearingwhenever thev engine throttle is opened wide as by pushing the accelerator pedal all the way to the floor, with the car traveling in high gearand below a predetermined speed.

An object related to that last stated is to provide im proved andsimplied l0ck-out means for the kick-down shift when the vehicle istraveling in high gear above a predetermined speed.

A still further object is to provide improved means whereby thetransmission may be selectively operated p in one of the lower gearratios with either a free wheeling Fig. 5 is a sectional view takensubstantially on the line 5-5 of Fig. 3 and looking in the direction ofthe arrows;

Fig. 6 is a sectional view taken substantially on the line 6-6 of Fig. land looking in the direction of the arrows;

Fig. 7 is a sectional view taken substantially on the line 7-7 of Fig. 6and looking in the direction of the arrows;

Fig. 8 is a detail elevational view taken substantially as indicated bythe line and arrows 8--8 of Fig. l;

Fig. 9 is a diagrammatic View of the hydraulic control system and therelated mechanical components;

Figs. l0, l1, 12 and 13 are similar longitudinal sectional views of themain speed control valve assembly, showing the same in differentpositions occupied thereby during operation; and

Fig. 14 is a fragmentary diagrammatic sectional plan View of the handcontrol lever, taken substantially on the line 1414 of Fig. 9.

Referring now to the drawings:

GENERAL ARRANGEMENT In broad outline, the principal components of thetransmission mechanism comprise a clutch group enclosed in a casingformed by a ilywheel housing portion 84 and a complementary bell-shapedhousing portion 126, and planetary gearing and a gear train housed in anextension casing 86. The transmission is adapted to be secured to anengine as 116 through a mating flange 83 on the flywheel housing 84, andto be driven by the crankshaft 1 of the engine which has a ilywheel 2bolted to its flanged end within casing 84. The llywheel 2 is providedwith a rim 89 to which is attached, by means of bolts 94, acomplementary cover I8 with a disk-shaped drive member 7 included inbetween. The controlling means for the transmission comprises hydrauliccomponents, the

functioning of which will be considered after the details of themechanical components have been set forth.

The clutch-driving mechanism The iiywheel 2 and the cover 8 jointlysupport two clutch pressure plates 5 and 6 by means: of a number ofslidably mounted studs 3 and 4, respectively. The studs 3 as well as thestuds 4 are located in a forewandaft direction at the outer periphery ofthe housing formed by the flywheel 2 and the cover 8, and have forkedheads 98 and 99 projecting through and outwardly from the rear face ofthe cover 8. Hardened pins 11 and if, respectively, are inserted throughheadsv 98, 99, the opposite ends of the studs being supported and guidedin the flywheel 2. The pressure plate has a number of lobes 5A on itsperiphery formed with openings 5B therein into which the studs 3 arepress fitted and against which the studs are shouldered by means of aange 96 formed on each stud. The studs also project through the pressureplate and are slidably iitted in openings 2A in the flywheel. Similarly,the studs 4 are pressed into the pressure plate 6, and have a shoulderedbearing upon it at 97 under their heads 99.

The flywheel 2 and the pressure plate 5 have opposed faces 90 and 91,respectively, between which a clutch plate 15 is included forengagement. This clutch as a whole, which may be termed the front or lowspeed" clutch is generally designated by the numeral 15. The disk 7 andthe pressure plate 6 have opposed faces 92 and 93, respectively, betweenwhich a clutch plate 16' is similarly included, and this clutch, whichis termed the rear or second speed clutch, is generally designated 16.

- T he clutch-operating mechanism Clutching and release of the plates15' and 16; are accomplished by axial movement of the studs 3 and 4,respectively, toward and from the ywheel 2, either independently of eachother or in unison. Engagement of clutch 15 alone establishes low orfirst gear; engagement of clutch 16 alone establishes second orintermediate gear, and simultaneous engagement of both clutchesestablishes high gear or direct drive.

For actuating the studs 3 and 4 to engage the clutches in the abovemanner, two groups of hydraulic cylinders are embodied in the side ofthe cover 8 away from the flywheel 2, one of which groups is generallydesignated 22 and comprises cylinders 22a, 22h and 22C, and the other ofwhich groups is generally designated 23y and comprises cylinders 23a,23b and 23C. The cylinders are all substantially identical and aregrouped closely around a cylindrical hub 100 which is integral with therotating cover 8, and which provides means for supplying pressure oil tothe cylinders of groups 22 and 23 from the outside.

Each of the cylinders in both groups 22 and 23 has a piston as 21slidably assembled in it to be acted upon by the oil and each isarranged to actuate, in turn, a double ended lever. The leversactuatable by cylinders 22a, 22h and 22e are designated 10 and thelevers actuable by the cylinders 23a, 23b and 23C are designated 12.These levers have as their fulcrums pivot pins as 9 mounted in closeproximity to the studs 3 and d as in lugs 95 cast on the cover 8.

Each of the levers and 12 has one long fingershaped arm reachingradially and inwardly into its corresponding cylinder, wherein itscontacts the piston as 21, and one short arm which bears with a llatside as 101 against a pin in its appurtenant stud, that is, with thepinr 1-1` in the stud 3, in the case of levers 10, While in the case oflevers 12, the side 102 bears against the pin 13 in the stud 4.

For disengaging the clutches and 16, the studs 3 and 4 are shiftedaxially back to their free positions by helical compression springs 26and 27 arranged upon the studs 3 and 4, respectively, springs 26reacting upon the pressure plate 5 on one side and the flywheel 2 on theother, and spring 27 reacting upon plate 6 and the iiywheel.

Clutch oil pressure generation and distribution Oil under pressure foractuating the pistons 21 is non mally supplied by a front orengine-driven pump 38 which can be of any well-known or suitable type,and which is contained in a housing 103 embracing the hub 100. Hub has asplined end 24 which mounts the pump rotor 88'. A pump intake port 122communicates with a passage 123 leading down to bottom of the gear case86 for bring oil from the sump to the suction side of the pump rotor 88.A port 124 in the housing 103 serves for discharge of oil under pressureby the rotor 88 into a passage 125 and thence into a line 129 whichleads to external ratio controlling means for the transmission. Apreferred arrangement of the ratio controlling means will presently beconsidered.

From the ratio controlling means oil is delivered back into thetransmission through two lines 127 and 128 which connect with passages104 and 105, respectively, in the pump housing 103. Passages 104, 105extend to the housing 103 and extension passages designated 104', 105',respectively, extend through the hub to its central bore, where theyregister with grooves 106 and 107, respectively, formed in the peripheryof the rotating hub 100. Sealing rings are provided in the hub 100alongside of the grooves 106 and 107 to prevent loss of oil, and it willbe seen that the hub also serves as a manifold for conducting uid to theclutch actuating cylinders.

From the grooves 106 and 107 pressure oil is conducted to the two groupsof cylinders 22 and 23 by passages 117 and 1197 respectively, leadingbehind the pistons 21 therein.

In order to salvage any oil leaking out past the pistons 21 or the rings44, a sleeve 14 is pressed over the cylinder group, and extends from thecover 8 into a flanged ring 30 secured to pump housing 103. Sleeve 14has a free edge 108 at its end which projects into ilanged ring 30, andthe ring 30 carries sealing means 30 upon its inner surface whichprojects over the end of the sleeve 14. Oil thrown off by the edge 10Sis caught in the ring 30 and drained back into the gear case 86 throughpassage 25.

In order to provide an oil tight closure around the inner ends of thelevers 11 and 13 and yet allow them to swing on their fulcrum pins as 9when acted upon by the pistons 21, ferrules 2S are embodied in thesleeve 14 around the projecting ends of the levers 10 and 13, and rubberboots 29 are slipped over both the levers and the ferrules 28 to closeyieldingly the clearance space between them.

T he clutch driven mechanism The two clutch plates 15 and 16 are securedto their respective splined hubs 17 and 18, the hub 17 being carried ona central shaft 19 extending through the whole length. of thetransmission from the flywheel 2, wherein it is supported in a. bearing109, to the end or" the gear case 86 ywhere it is carried indirectly intwo bearings 41 and 43. Inside the gear case S6 the shaft 19 is formedwithV a gear 87 which is herein further referred to as the sun gear.

The clutch plate 16 engages by means of its splined hub 18 a tubularshaft 20 which is rotatably supported on the central shaft 19. The shaft20 extends through the hub 100 into the gear case S6 where it carries ahardened multi-toothed cam 33, shown as integral, for a one-waycoupling, and next to it a radial flange 110 which mounts and drivesthrough toothed engagement therewith an internally toothed gear 35 whichis concentric with the sun gear 87.

T he planetary gearing The sun gear 87 and the internal toothedv gear 35are members of a planetary gear set by the use of which, through theinstrumentality of the clutches 15, 16, three different speed ratios areobtained.

Inteiposed between the sun gear 87 and the internall toothed gear 3S arethree planet. gears 36 which run on aver/,sar

bearings 38 and shafts 37 in a carrier cage' 39. The cage 39 is integralwith a tubular shaft 40 which is'ro. tatably mounted on the tail portionof the central shaft 19 and is supported in two bearings 41 and 43. Therear extremity of the shaft 40 is provided with splines 113.

Mounted on the shaft 40 between the bearings 41 and 43, and driven bythe splines 113, is a gear42 which is in engagement with other gears inthe gear case 86 for transmitting power to the nal drive.

The one-way couplings Two one-way brakes are embodied in the mechanism,on on each of the shafts 19 and 20, to provide reaction means, each ofwhich is adapted tohold its appurtenant shaft against unwanted reverserotation. i

The one-Way reaction rake for the shaft 20 is located adjacent its angedend 110, and may be of any of the well known types, such as the rollertype shown. The inclined teeth of the cam member of the brake aredesignated 33, the smooth internal circular raceway 82 around the camteeth 33 is formed in a stationary member 31, which serves also as aclosure for the oil pump 88, and the rollers 32 are interposed betweenthe teeth 33 and the raceway 82 in the usual manner, the rollers beingretained in their angular spacing and axial positioning by a cage 34.

The rollers will be loose when propelled around by the abrupt or morenearly radial anks of the teeth 33, when the shaft rotate in its normaldirection, while whenever the driving torque is reversed, the rollersare wedged and the shaft 20 stopped and held, as will be apparent.

The one-way reaction brake for the central shaft 19 and the sun gear 87thereon is located at the rear end of the shaft next to the bearing 43,and similarly comprises a conventional roller brake including a hub 49in splined engagement with the shaft 19 and having toothlike cam teeth48 cut in its periphery. The internal smooth cylindrical raceway 50 isprovided around the hub 49 in a flanged member 45 which is bolted to theend of the gear case 86 and provides a support for the bearing 43.Rollers 46 are guided by a cage 47, and the brake acts in like fashionto arrest reverse rotation of the shaft 19.

The device for using the engine us a brake A disk type friction brake isemployed to enable the mechanism above described to convey torque in thereverse direction from that in which it flows normally when the engineis driving. This permits using the engine as a brake for the vehiclewhen descending hills.

This function obtains automatically when the transmission is in highgear, but not when it is in either one of the two lower gears, but meansis provided whereby intermediate, or second, speed may also be employedfor engine braking.

A plate 55 is fast on the rear end of hub 49 of the one-way brake andlies close to closure plate 58 which closes the rear end of the case 86,the plate 55 being engaged with splines 57 on the hub 49 for angulardrive but axial freedom of movement. The plate 55 is provided withfriction facing 56 on both sides.

The plate 55 is a locking brake for the shaft 19, and to perform thisfunction, by means of pressure oil, an annular piston 52 is embodiednext to the plate 55 on the opposite side thereof from cover plate 58,adjacent the bearing support 45, and is axially movable to force theplate 55 against or loosen it with respect to cover plate 58. Piston 52is anchored angularly to the bearing support 45 as by dowel pin 51, andis held normally disengaged and against the bearing support 45 by anum-` ber of hai1pin springs 54 lodged between the piston 52 and thecover 58 around the plate 55.

Oil under pressure is fed from the outside controll means to the spacebetween the piston 52 `and the bearing support 45 through a'passage 53.The piston 52 is thereby forced against the pressure of the springs 54toward the plate 55 which it compresses between piston face 112 and theinner face 111 of cover plate 58.

Final drive and reverse gear The drive from gear 42 is conveyed to thenal drive shaft 69 through an intermediate gear 60 on a shaft 63, and inall forward speeds the drive passes from gear 60 to a gear 67 on theshaft 69, a dog clutch 75 and '74, and through splines 70 to the shaft69.

The intermediate gear 60 is integral with sleeve portion 59 whichconnects it with a spaced gear 61 at the opposite end of the gear case86. Sleeve gears 60 and 61 are mounted rotatably on the shaft 63 bymeans of bearings 62, shaft 63 being locked against turning by a key 64in the Wall of the gear case 86.

The gear 61 is in constant mesh with a reverse idler gear 65 supportedon a shaft 66 in the gear case 86.

The final drive shaft 69 is mounted in two bearings 77 and 78 near itsextremities, and has a bearing portion 68 adjacent the bearing 78 onwhich the drive gear 67 can rotate freely when the shaft 69 is driven inreverse speed. The shaft portion adjacent the bearing 77 is providedwith splines '70 on which a gear 71 is slidably mounted. The gear 71 hasgear teeth 72 engageable with the reverse idler gear 65, internal dogclutch teeth 74 engageable with complemental teeth 75 on the main drivegear 67, and a groove 73 in which a shifter fork 118 operates.

The shaft 69 projects at both ends beyond the bearings 77 and 78, andthe projecting ends are provided with splines and 80, respectively. Thesplines 86 serve to mount a universal joint 81 for delivering power forvehicle propulsion. The splines 115 at the opposite end serve to mountand drive the rotor of the rear oil pump generally designated 79 andarranged in a housing 114 on the side of the gear case 86. The intake ofoil for this pump is through a suction passage 85 at the bottom of thegear case 86, and discharge and delivery of pressure oil is through aport 138 and a line 139 leading to the outside ratio control means (seeFig. 8). The fluid from the two pumps is handled in a manner to bedescribed. `A check valve 138A in the line 13S prevents the auxiliaryoil pump from drawing oil back to the sump when the vehicle is operatedin reverse.

Gear shifting mechanism The sliding axial movement of the gear 71 isperformed by means of the shifter fork 118 between the following threeoperative positions: (l) Extreme righthand position as viewed in Fig. l,shown in broken lines in that view and designated 71a, wherein the dogclutch teeth 74 are in mesh with the teeth 75 on the main drive gear 67(2) a neutral position shown in full lines wherein neither the teeth 74nor the teeth 72 are in mesh, and (3) an extreme left-hand positionshown in broken lines and designated 71b, wherein the teeth 72 are inmesh with the reverse idler gear 65.

In order to obtain the above three positions of the gear 71, the shifterfork 118 is carried pivotally in a lever arm which oscillates around itsfulcrum stud 136 supported in the gear case 86, and has a lever 137secured to it on the exterior of the gear ease for controlled operation(see Fig. 6). The three functional positions of the gear 71 arepredetermined by three detent grooves 133, 134 and 135 in the peripheryof the lever arm 130, in any one of which grooves a ball 131, backed bya spring 132, can yieldably hold the lever arm 130, the shifter 118 andthe gear 71 against independent motion.

FUNCTIONAL DESCRIPTION OF THE TRANSMISSION The various component partsof the transmission c`o-` act to impart three different forward speedsto the final drive shaft, and also make it possible to use the powersource as a brake for the vehicle in two of the forward speeds. Thesefunctional relationships of the various parts will be described withreference to each specific result that they produce.

Engine running, vehicle standing When the vehicle is at a standstill andthe engine crankshaft is rotating, the power can be disconnected at twodistinct points, i. e., (l) by releasing both of the clutches 1.5 and16, and (2) by shifting the gear 71 on the drive shaft 69 into theneutral position in which it is shown in full lines in Fig. l.

ln the first instance, i, e., complete release of both frictionclutches, all the shafts and gears in the transmission stand still, therotating parts being the flywheel 2, the clutch cover 8, and all theparts mechanically attached thereto, such as the hub 100, the cylindergroups 22 and 23, the oil sleeve 14, the levers 10 and 12, the studs 3and 4, and the pressure plates 5 and 6. The oil pump rotor 8S is alsobeing driven, and the oil that it supplies, instead of being fed intothe cylinder groups 22 and 23 for energizing the clutches, is by-passedand dumped back into the gear case $6.

In the other instance, i. e., the gear 71 in ther neutral position, andboth clutches engaged, all the shafts and gears in the transmission arein motion except `the final drive shaft 69 and the gear 71 on it.

Transmission in low gear By shifting the gear 71 toward the final drivegear 67 by the shifter 118, the dog clutch teeth 74 and 75 couple thesegears together, and by directing pressure oil into the cylinders 22a,22h and 22e while withholding it from the cylinders 23a, 23h and 23C,through the agency of suitable control means presently to be considered,the lowest speed ratio will be obtained.

The pressure oil will displace the pistons 21 outwardly toward the openend of the cylinders 22a, 22b and 22C thereby causing the levers 10 topivot about their fulcrum pins 9 and apply pressure on the pins 11 bytheir lever arms 101. The pins 11 will force the studs 3 to slide aX-ially toward the flywheel 2, thereby exerting pressure on the plate 15by the shoulder 96, and compressing the plate 15 between the face 91 andthe4 face 90 on the iiywheel 2.

The clutch plate 15 will transmit the rotation and torque to the shaft19 and the sun gear 87 thereon, which would normally cause the planets36 meshing with it to rotate around their shafts 37; however, theseplanets are also in mesh with the internal toothed gear 35, and sincethe planet carrier cage is part of the final drive and is 0fferingtorsional resistance to motion, the reaction of the planet teeth againstthe teeth of the internal toothed gear 35 tends to give this gear abackward rotation opposite to that of the sun gear 87. This backwardrotation of the internal toothed gear 35 will bring into action, in aninstant, the one-way coupling rollers 32, which will jam between theteeth 33 and the raceway 82, thereby arresting the motion of theinternal toothed gear 35, the shaft 2t) and the clutch plate 16'connected with it.

With the internal toothed gear 35 thus functioning as the stationarymember in the planetary gearing, the planets 36 will revolve around thesun gear S7 and propel the carrier cage 39, the shaft 40 and the gear 42around forwardly at a reduced speed from that of the sun gear 87.

The rotation of the gear 42 is transmitted to the final drive shaft 69through the intermediate gear 60 to the nal drive gear 67, and from itinto the shaft 69 through the dog clutch teeth 75 and 74 and splines 70thereon.

Transmission in second gear To effect an intermediate or second speeddrive, the clutch 15 is released and clutch 16 is engaged by energizingthe cylinders 23a, 23h and 23e. This causes the pistons 21 of cylindergroup 23 andthe levers 12 to exert pressure on' the pins 13 of the studs4,A whereby these studs will push the pressure plate 6 into engagementwith the clutch plate 16 and clamp the latter against the face 93 of thedriving disk 7.

The clutch plate 16 drives the shaft 20 and the internal toothed gearconnected to it. With the planet carrier cage 39 offering resistance torotation, the planets 36 will begin to accelerate the sun gear 87 in theopposite direction of rotation from that of the shaft 20, but in thisthey will immediately be restrained by the one-way reaction brakerollers 46, which rollers will be wedged between the` teeth 57 and theraceway 50, and will prevent any counter rotation. With the sun gear I87thus secured as the reaction point, the planets 36 will revolve aroundit and. impart to their cage 39, the shaft 40 and the gear 42 a reducedforward speed somewhat higher `than the speed in the previous case ofthe low gear drive.

From the gear 42 to the final drive shaft 69 the same parts perform thesame functions as in the case of the aforementioned low gear drive,

Transmission in "high gear This condition is often referred to as directdrive, and implies the least reduction of speed between the engine andthe vehicle axle. To this end both of the clutches 15 and 16 are broughtinto engagement through the instrumentalities above described inconnection with each individual clutch, which means that the pistons 21of both cylinder groups 22 and 23 Will be energized simultaneously bypressure oil. Consequently, the two shafts 19 and 20 will rotate inunison, as will the sun gear 87 and the internal toothed gear 35. Therebeing no relative motion possible between these two gears, they willrotate, to-

gether with the planets 36 between them, as a single body,

as will the planet carrier cage 39, the shaft 40 and the gear 42.

In this relationship, therefore, there is no reduction or increase inthe speed of the crankshaft 1 up to this point; any such alteration ofthe crankshaft speed can be effected between the gear 42 and the naldrive shaft 69 by proportioning the gears 42 and 67 suitably in size tothe direct drive requirements.

Transmission in reverse gear By shifting the sliding gear 71 on theshaft 69 from its neutral position into position 71b, its teeth 72 willbe brought into mesh with the teeth of the reverse idler gear 65, andthe power is then conveyed from the gear 42 through the gears 60 and 61to the reverse idler gear 65, to the sliding gear 71, and throughsplines to the drive shaft 69. The main drive gear 67 becomes an idler.

It will be seen that the shifting of the sliding gear 71 for reversedrive into position 71h might be effected in any one of the threepreviously mentioned forward speeds, i. e., with either one of the twoclutches 15, 16,

or both of them, engaged, and three different reverse gear ratios arehereby obtainable. For passenger car operation it would be sufficient touse only one reverse speed, of the lowest ratio, by engaging clutchplate 15 which yields the low forward speed, and reducing this speedstill further by suitable proportioning of the gears 61 and 72.

Using the engine as n brake With the transmission in high gear, when theengine speed is reduced, the momentum of the vehicle will propel thefinal drive shaft 69 and thus reverse the application of torque on allgear teeth in engagement, though not reversing the direction of rotationof any of the shafts.

When the transmission is in high gear, both clutches 15 and 16 areengaged, and if the shaft 69 becomes driving instead of driven, i. e.,if the torque from the outside exceeds the torque produced by thecrankshaft 1, no operational change takes place, both clutches 15 and 16transmitting `the, driving power of the vehicle to the crankshaft 1to-be absorbed by the' pumping action of the engine,

grauer t is often found necessary to utilize increased braking action ofthe engine with the transmission in second gear, as when descendingsteep hills. In that case, the transmission disclosed hereinabove hasthe clutch 16 in engagement while the clutch plate 15 is being heldstationary by the one-way reaction brake rollers 46. Should the torquedirection be reversed on the teeth of the planets 36, it would make themchange their point of reaction from the sun gear 87 to the internal gear35, because the latter would be driven by the carnkshaft 1 at a slowerspeed than the planet cage 39 and, consequently, the planets 36 wouldset the sun gear S7 and the shaft 19 in motion in their normal directionof rotation; this action would disengage the shaft 19 from its arrestedposition by the one-way coupling rollers 46, and would make it spinfreely because its clutch plate 16 is not then engaged, and no positiveconnection between the nal drive shaft 69 and the crankshaft 1 forbraking action by the engine would exist.

In order to provide such a connection, and thus make it possible to usethe engine as a brake when the transmission is in second gear, thefriction braking plate 55 is made use of. By energizing the piston 52with pressure oil through passages 53, the piston compresses the facings56 between its thrust side 112 and the inner side 111 on the cover 58,and prevents the shaft 19 from rotating, thereby establishing a reactionpoint for the planets 36 when their carrier cage 39 is driving, andenabling the provision of a two-way second gear drive whenever theengine braking action is required in that speed.

CONTROL SYSTEM: FLUlD SUPPLY SYSTEM AND MAIN CONTROL VALVE From theengine driven or front pump 3S uid is conducted through conduit means129 to a port 265 extending through the side of a valve body 296 withinwhich a main control valve element 208 is axially slidable. A sleeve 210is provided in the body forming a replaceable bearing for the valveelement and carrying the inwardly opening channels with which thechambers and spools of the valve cooperate. The valve assembly isordinarily urged to the right (as viewed in Figs. -13 inclusive) as faras the iirst speed position shown in Fig. l1, by compound spring meansincluding the two helical compression springs 214, 216, while a coactingspring 212 opposes movement of the valve farther to the right, or fromAthe rst speed position of Fig. l1 to the neutral position of Fig. l0.The action of spring 212, 214, 216 will presently be considered ingreater detail, but it is to be noted that the valve is movable inpredetermined steps, the proportions of the stepwise movements beingdelineated by detent means including a spring pressed poppel: 218slidable in a lateral bore 220 in the side or the valve casing 206 andurged by means of its detent spring 22d into engagement with notches 222formed in the valve. The valve is thus movable in step fashion to divertthe iiuid supplied through the conduit .129 and port 205 in such manneras to cause engagement of either of the clutches 15, 16 independently,or both of such clutches simultaneously, as may be required to establishany of the several gear ratios in the manner previously described.

The valve is automatically movable under the iniuence of vehicle speed,although such automatic action may be modified under certain conditionsor when the driver desires. The means for moving the valve willpresently be discussed, but consideration will iirst be given to theseveral positions which the valve occupies, and the tluid ow in each ofsuch positions.

In Fig. 10 the valve is shown in neutral position and at such time thefluid from the engine driven pump 88 enters valve chamber 226 throughport 205, flows through a port 228 arranged opposite the port 205, andthrough a longitudinal bore 230 in the valve casing to a radial port232. Port 232 is then in communication with valve 10 chamber 234, butthis chamber is sealed off since the valve spools 242, 244 then engagethe .interior of the sleeve 210 upon either side of the internal channel256.

With the valve in this position, the fluid supply systems connected toboth of the clutches 15, 16, or more exactly to the actuating cylinders22, 23 for the clutches 15, 16 respectively, are vented to atmosphere.Conduit 127 which is connected to the actuating cylinders 22a, 22h, and22a` for the irst speed clutch 15 is connected to a port 260 in the sideof the valve casing 206, while conduit 128 which leads through passagespreviously described to the actuating cylinders 23a, 23h, and 23C forthe second speed clutch 16 is connected to a port 262 also formed in theside of the valve casing 206 at a spaced point. The valve body 208 isprovided with an axial bore 265 closed at both ends. A radial bore 266provides communication between the axial bore 265 and valve channel 268between valve spools 236, 233, while a similar radial passage 270provides communication between the axial bore 265 and valve chamber 272located between spools 244, 246. Any iluid pressure within the low speedforward drive clutch 15 actuating cylinders of group 22 and theirconnected conduit 127 is vented through port 266, valve easing chamber25S, valve channel 272, and vent port 275 which is then uncovered by theregistering of valve channel 272 therewith. Vent port 275 may, ofcourse, have a return connection (not shown) to the sump for theactuating lluidl supply, which sump is indicated as comprising thebottom of the gear case 86. Second speed forward drive clutch 16 and itsconnected conduit 128 are at the saine time vented to atmosphere by wayof valve passage 262, valve casing channel 25d, valve chamber 26Slocated between valve spools 236, 238, and by way of the axial bore andconnected passages 266, 265, 270 to valve chamber 272 and thus to ventport 275. Since fluid pressure is thus cutoli from both actuating meansfor the two friction clutches and the actuating cylinders are vented toatmosphere, the clutches are held in the released positioning by theirrelease springs 26, 27 and the transmission is in neutral as abovedescribed.

When the valve 208 is moved one step to the left, to the position shownin Fig. 1l, the tluid entering through conduit 129 and port 265 passesthrough valve chamber 226 and passages 228, 230, 232 to valve casingchannel 256 and valve chamber 234 which then overlaps both the channel256 and the spaced channel 258 to which the port 260 and conduit 127leading to the first speed clutch 15 are connected. lt will be notedthat port 260 is at this time sealed oit from the exhaust passage 275 bythe spool 244, and pressure is thus supplied to engage the first speedclutch. The second speed clutch 16 remains disengaged by reason of thefact that the actuating cylin ders of the group 23 remain vented toatmosphere by way of conduit 128, port 262, and the internal valvechannels, chambers, and passages 256, 268, 266, 265. 270, 272, 275. Withthe forward clutch 15 engaged and the second speed clutch 16 disengaged,second speed drive is established in the manner previously described.

When the valve 208 moves to the left one further step, to the positionshown in Fig. 12, the forward clutch 15 is disengaged and the secondspeed clutch 1.6 engaged, to establish second gear drive. At this timethe first speed uid passage 266 and connected conduit 127 leading to thelow speed clutch actuating cylinders of group 22 is vented to atmospherethrough a branch passage 280 and a connecting radial port 282 formed inthe valve body and in communication with the low speed clutch pas sage260. Passage`282 is connected to valve sleeve channel 254. It will benoted that with the valve in this position spool 238 lies in sleevechannel 252 and is nar rower than this channel and centered with respectthereto, so that the channel overlaps both sides of and thus bypassesthis spool. Likewise spool 240 lies within and is spaced from both endsof sleeve channel 254, being narrower than this channel, which thenoverlaps both sides of the spool and so` in effect by-passes the spool.Communication is thus. established from port 232 past bothof the spools240, 238 and to the valve chamber 268 into which the vent port 266formed in the body of the valve opens. The fluid pressure in the tirstspeed clutch actuating system may thus escape through the axial bore 265to radial valve bore 270 and thus to exhaust passage 275. Supply oflluid under pressure to the second speed clutch is established from thesupply line 129 and port 205 directly through valve chamber 226 to valvechannel 250 connected, as previously noted, to valve passage 262, towhich the conduit 128 leading to the second speed clutch actuatingcylinder system is connected.

When the valve 208 moves to the left one further step, which is the lastposition and is indicated in Fig. l3, tluid conductive communication isestablished between supply conduit 129 and passage 205 and both clutchactuating cylinder groups 22, 23, so that both clutches become engagedto establish the high speed drive in the manner previously described.Communication to the rst speed clutch occurs by way or valve chamber226, passages 230, 232, valve sleeve channel 256, valve chamber 235located between valve spools 240, 242, valve sleeve channel 254 andpassages 232, '30, and 250 to the conduit 127 leading to the low speedclutch actuating means. Communication between the supply conduit 204 andthe conduit 12S leading to the second speed clutch actuating systemagain occurs as in the second speed drive directly through the valvechamber 226 which then provides communication between ports 205, 262.

it will be apparent that upon reverse movement of the valve toward theright and successively back to the positions shown in Figs. l2 and ll,the valve reassumes the previously described positions and successivedownshits resultantly occur to second and tirst speeds, while neutral isestablished when the position of Fig. l() is reached.

CONTROL SYSTEM: CONTROL VALVE ACTU- ATING MEANS-AUTOMATlC An extensioncasing cylinder 290 carried by one end of and coaxialv with the valvecasing 206 houses the actuating springs 212, 214, 216 and associatedmechanism s;

by which automatic longitudinal movements of the valve are induced. Astem 292 is attached to the end of the valve and projects axially intothe cylinder 290. At its end remote from the valve body the stem 292 isenlarged and chambered as indicated at 294. The enlarged portion of thestem is designated 295 and is provided with a smooth cylindricalexterior over which a hollow cylindrical piston 296 slidably tits. Atits outer end the piston 296 overlies the chamber 294 and the head ofthe piston carries keying means generally designated 298 serving tocouple to the piston an extension in the form of a piston valve 300.Piston valve 300 slides in a cylinder 364 formed in cylinder head 358.Fluid pressure in cylinders 290, 364 functions to vary the loading ofsprings 212, 214, 216 and thus influence the position assumed by thevalve 208.

Outward movement of the piston 296 is limited by a snap ring 302 seatedin an internal groove (undesignated) formed in the cylinder 290. Spring214 bears outwardly against the skirt of the piston sleeve 296, which iscounterbored as indicated at 304 to form a seat for the spring. Thespring is of the helical compression type. At its inner end spring 214seats against a flanged 'retainer 306 positioned by a snap ring 303 alsoseated in an appropriately positioned groove formed interiorly of andnear the inner end of the cylinder 290.

The control valve is moved to the extreme right-hand position, as viewedin Fig. l0, which puts the transmission in neutral, as previouslyexplained, by positive mechanical action, whenever through the agency ofneutral shifting means associated with the shift lever 320 and presentlyto be described in greater detail, the driver moves the linger piece 322away from the end of valve 208. Finger piece 322 is mounted in acombined cover and supplemental casing member 324 arranged at theopposite end of the valve casing 206 from that occupied by the cylinder290. The finger piece is adapted to bear against a headed plug 325carried by the end of the valve element 208 and serving as a closure forthe axial bore 265. The sleeve 210 is open at its end within cover 324to expose the end of the valve, and the valve is moved to the neutralposition shown in Fig. l0 only when positively actuated thereto by thefinger piece 322. Movement of the valve to such neutral positioncompresses the spring 212, and the force exerted by spring 212 when thevalve is in the neutral position is suiiicient to move the valve pieceback to the rst speed against the resistance of the poppet 213 when thefinger piece is moved away from the end of the valve, regardless ofwhether any fluid pressure exists in head chambers 356, 370.

Fluid pressure developed by the rear or propeller shaft driven pump 79is delivered through conduit 139 and through pressure limiting valves326, 328 and conduits 330, 332, to the cylinders 290, 364.

The valves 326, 328 are incorporated in a single casing 335 and theconduit 139 is connected to such conduit through metering means shown asa coupling element 336 having a restricted orice therein. From themetering element uid is conducted through a double branched conduit 338to valve 326 and to a passage 342 in the valve casing. Valve 326 is inthe form of an adjustable needle valve which controls the connectionbetween the inlet .conduit 338 of the casing 335, and an exhaust opening340 which is metered by the needle valve. It will be seen that i thepressure developed in the system beyond this point depends upon therestricttion provided by the needle valve. Passage 342 extends straightthrough the valve casing 335 and is connected to the conduit 330. Abranch passage 344 in the casing 335 connects passage 342 to acylindrical valve chamber 345 in which the cylindrical piston-type valve328 is slidable. Valve 328 serves as a throttling valve by which afurther pressure drop may be imposed between the pressure present inpassage 342 and that in conduit 332. When valve 323 is moved upwardly,as viewed in Fig. 9, its peripheral chamber 346 moves in a direction toclose off the passage 344 and so interrupt communication between passage344 and passage 348 to which the conduit 332 is connected, while whenthe valve is moved downwardly the edective cross sectional area of theconnection between passages 344 and 348 is increased. The valves 326 and328 may be selectively actuatable by the driver as by means of suitablecontrols (not shown) mounted upon the instrument panel of suitablecontrols (not shown) mounted upon the instrument panel of the vehicle,and by Bowden wire means connected thereto and fragmentarily indicatedat 350, 352. Conduit 330 is connected to the side of the valve casing206 in such manner as to communicate with a passage 355 in the valvecasing, and with an extension passage 355' located in the casingcylinder 290 and forming a continuation of the passage 355. Bore 355leads to the outer end of the cylinder where it communicates with headchamber 356. The pressure thus delivered to chamber 356 acts upon theouter end of piston 296, as will be apparent, the end of cylinder 290being closed by the head 35S attached in sealed relation thereto.

Pressure fluid delivered from the rear pump by way of throttling valve328 and conduit 332 is led to a port 360 formed in the valve casing 206.An extension 360 of the passage 360 is formed in the cylinder 290 andcommunicates with a further extension portion 360g drilled or otherwiseformed in the head 358. At its outer end passage 3602 communicates withan internal channel 362 formed in the inner periphery of the cylindricalopening 364 in the head 358, in which opening the piston valve element300 travels. An axial bore 365 is formed in piston valve 3d@ inwardlyfrom the outer end thereof. Axial bore 365 communicates with a radialpassage 366 and peripheral piston valve channel 368 so that with thepiston valve in certain positions communication is established betweenthe head chamber 370 at the outer end of the piston valve and thepassage 3662.

A channel 372 formed in and nearer the outer extremity of thecylindrical opening 364 in the head is adapted to he uncovered by thepiston valve 300 when it and the connected piston 296 move inwardly tothe positions they assume in moving control valve 208 to the higherspeed positions. Channel 372, which is thereby at such times placed incommunication with the head space 37d, communicates with a head passage374 which is connected to an extension 374 of such passage, theextension being located in valve casing 266 and leading to an exhaustopening 375.

When the finger 322 moves away from plug 325 by the hand shifting means,spring 212 expands, moving stem 292 and the connected valve 208 to theleft, as viewed in Figs. l and ll, from the position of Fig. l0 to theposition of Fig. ll. The shoulder 378 formed by the enlarged chamberedportion 295 of the stem 292 then comes up against a stop formed by asnap ring 380 seated in a suitable groove (undesignated) inscribedwithin and near the free extremity of the skirt of piston 296. Thisoccurs as the poppet 218 drops into the second notch 222 and the lowgear forward drive position of the valve is reached, as shown in Fig.1l. The vehicle may now be accelerated in low gear, and the resultantoperation of the rear pump '79 develops pressure in connected con duit139.

The pressure builds up in the valve casing 335, assum ing that theneedle valve 326 is closed far enough to permit such build-up ofpressure, as is normally the case. Pressure communicated through conduit330 enters cylinder space 356 by way of passages 355, 355 and alsoenters head space 370 by way of valve 328, conduit 332, and passages360, 360 and connected ports and passages 368, 366, 365. When thevehicle reaches a predetermined speed, suicient leftward pressure isthereby exerted upon the piston 296 and piston valve 300 to compressspring 214 and move the stem assembly 292, 295 to the left a distanceequal to the spacing of one of the notches 222, which movement alsobrings the skirt of the piston 296 into engagement with a ring 390 whichforms a seat for the outer extremity of spring 216. The valve 203 thusassumes the position shown in Fig. l2, in which the fluid system isarranged to institute and maintain the second gear drive, in the mannerpreviously described.

lt will be noted that as the piston valve 300 moves to the left from thefirst speed position of Fig. 1l toward the second speed position of Fig.12, uid supply channel 362 is cut oil?, so that the only effectiveliquid pressure exerted upon the pistons and upon the valve 208 is thatresulting from pressure delivered to cylinder 356 by Way of passages35S, 355 and connected conduit 330. When this pressure reaches suchproportion as to overcome the resistance of spring 216 and of the poppet218, which it does at a predetermined further increase of car speed, thevalve 26S is snapped to the left one further position, compressing thespring 216 as the skirt of the piston 296 forces the ring 390 inwardly.As the piston valve 300 moves to the left-hand or high speed positionshown in Fig. 13, the channel 372 is uncovered, venting head space 370to atmosphere by way of passages 374, 374 and exhaust port 375, Channel362 remains sealed olf, the entire fluid supply for movement of thevalve assembly to and maintaining the same in the high speed position isderived from conduit 330, the pressure in which is regulated only by theneedle valve 326 and metering port 336.

lt will be apparent that the speed at which the shift from first speedto second speed occurs is variable by adjusting the positioning ofthrottling valve 328, since the pressure derived by way of this valve isexerted in head chamber 370 only during thc shift from hrst to secondgear. The speed at which all automatic shifts occur may be regulated byadjustment of the needle valve 326 which, as will be apparent, variesthe pressure of the fluid supplied through both of the conduits 330 and332.

As shown in Fig. 9, the hand lever 320 is movable in a planesubstantially parallel to that of the steering wheel 400, to rock theshifter shaft 402 around its axis through a limited are of movement. Theshifter shaft lies alongside the steering column which is generallydesignated 404 and indicated as arranged in the conventional manner. Anarm 405 is secured to the lower end of the shaft 402 and articulated asby means of a link 406 to a bellcrank 403 which is, in turn, connectedby means of the link 410 to operating arm 137 for theforward-neutralreverse shifter yoke 118. At one extremity of its angularmovement, therefore, the shifting lever 320 lies in a forward positionin which the yolre 118 maintains the shiftable clutch gear element 71 inthe position 71a, in which the teeth 74 and 75 are engaged and theforward drives are effective, as previously described. At the otherextremity of its movement the control lever 320 lies in a reverseposition, the gear teeth 72 being thereby engaged with the reverse idlergear 65, as the clutch gear assembly 71 then lies in the position 71band reverse drive is effective, as previously described.

Also coupled to the bellerank 403 as by means of a link 412 is a dumpvalve 415 arranged to vent the pump 8S at all times when the shiftinglever 320 is in the neutral position intermediate its forward end.reverse positions previously described. The dump valve is also of thebalanced piston-type, connected to the output of the pump 8S by a branchconduit 129', which enters the dump Valve casing 414 in a centralposition and opens into a central chamber 416 therein. The valveelement, generally designated 415, is provided with a central spool 420and spools 422, 424 at its ends. The valve casing is also formed withchambers 42S and 426 spaced from the central chamber 416 by reducedareas 428 and 430 which the spools of the valve accurately and slidablyfit. When the valve element 415 is in the centered position, it occupieswith the shift lever in neutral, the conduit 129 is connected to theexhaust ports 432 and 434, while when the valve is moved in eitherdirection the port 2042 is isolated, permitting the pump 88 to build uppressure in the line 129 and actuate the hydraulically shiftable controlvalve and related elements in the manner previously described.

It will be noted that the neutral position of the shift lever 320previously described releases the clutch gear assembly 71 fromengagement with both the forward and reverse driving means, and soeffects a mechanical neutral, while at the same time releasing the luidpressure through the agency of the dump valve 415. Under someconditions, particularly in extremely cold weather, this may notcompletely release all pressure in the hydraulic system, and anadditional neutral arrangement, which may, if desired, be used as analternative to the neutral means already described, is shown in the formof means for actuating the linger piece 322 in such manner as to causethe main control valve 208 to move to the neutral position of Fig. l()in the manner previously described. This may be effected by means of amanually operable button 440 mounted upon the end of the shift lever 320and movable in and out in a line parallel to the axis of the shiftlever. The button 440 is fast upon the end of a rod 442 extendinglongitudinally inwardly through the shift lever and through and beyondthe axis of the shifter shaft 402. At its inner end the rod 442 carriesa button-like tip 444 engageable with an enlarged pad 445 carried by one`arm 448 of a bellcrank pivoted on the steering column, as by means ofthe transverse pin 446. The other arm 448 ofthe bellcrank is connectedby means of a link 450 which extends longitudinally down the steeringcolumn to a second bellcrank 452 pivoted upon a pin 454 at the bottom ofthe steering column. Additional means completing mechanical connectionto the finger piece 322 include the link 455 and a bell crank 456, onearm 458 of which is adapted to bear against an arm 460 fast upon theshaft 462, to which shaft the linger piece 322 is also attached. Ahelical tension spring 464 reacts upon the bell crank 452, tending toswing it in such direction as to urge the valve 208 toward neutralposition and to move the button 440 outwardly, the outer position of thebutton representing the neutral position. A ball detent element 465urged outwardly by a leaf spring 466 into either of two pockets 468 and470 interiorly formed in the cylindrically counterbored outer end 472 ofthe shift lever 32) serves as means for holding the button 'in eitherposition. A cylindrical enn largement 474 of the rod 442 houses thedetent ball 465 and its actuating leaf spring 466, and constitutes meansfor attaching the button 440, which is threaded into the tappedextremity of the hollow cylindrical portion 474. The leaf spring 466, asshown in Fig. 9, may be carried by the threaded boss portion 475 whichserves as attaching means for the button. The total resistance offeredby the detent 465, spring 464 and detent 218 is sufficient to maintainthe valve 205i in the neutral position shown in Fig. l0 against the eortof the spring 212. When the finger piece 322 is moved away from the pad325 on the end of valve 208, however, by pushing the button 440 into theinner or starting position, the spring 212 overcomes the resistance ofthe poppet 218 and valve 208 moves to the forward drive low-speedposition of Fig. ll as previously explained.

It will be apparent that successive up-shi'fts, during normalacceleration of the car forwardly, lare the result of increasingpressure developed by the rear pump 79, and that such pressure is afunction of car speed. Downshifts ordinarily also occur as a function ofreducing car speed, as the pressure developed by pump 79 falls away,although it will be apparent that downshifting is delayed by the actionof the poppet 218 so that once a higher speed ratio has beenestablished, the car may be decelerated considerably without immediatelycausing a downshift. In order to provide an automatic kickdown shift toa lower speed when the throttle is opened wide or the accelerator pedalis pushed down to a predetermined position, means is provided forpositively moving the valve 208 from high speed to second speed positionwhen the accelerator pedal is moved to or beyond full throttle opening.Such means comprises an arm 480 fast upon the shaft 462 and engageableby a iinger piece 482 actuatable by means of a link 484 coupled to thearm 482 and also coupled to an arm 485 secured to and moveable with theaccelerator pedal 486. Arm 485 may swing co-axially `about the shaft 488upon which the accelerator pedal is pivotally mounted.

Means may also be provided for preventing a kickdown shift when thevehicle is traveling above a predetermined speed in high gear. The speedat which the kickdown lockout action becomes effective is, of course,selected in such manner that the kick-down is locked out at the speedabove which increased acceleration would not be obtainedl from adownshift. The lockout means is indicated as comprising a hydraulicallyactuatable piston element i90 mounted in ya cylinder 492 and having astem 494 projectable from the cylinder to engage Van arm 495' rigidlysecured with respect to the arm 482 and shown as attached to the samepivot pin 496. Piston and stem assembly 49? and 494 are shown as urgedinwardly, in a direction tofree the arm 495, by a helical compressionspring 498 housed in the cylinder 492, the piston and stem being movableoutwardly to a position in which they block movement of the arm 482 tothe position corresponding to the second gear position of the valve 208,by hydraulic pressure supplied by the rear pump 79. For this purpose thespace within the cylinder 492 below the piston 4% is connected to theoutput conduit i3@ from the rear pump by means of a branch conduit 1392.When the pressure developed by the rear pump exceeds a predeterminedvalue corresponding to a selected car speed determined as above noted orotherwise as the designer or engineer may prefer, the resistance ofspring 498 is overcome, and stem 494 moves outwardly, blocking movementof the arm 482 to a position which would cause a downshift, although itwill be apparcnt that for a certain range of speed within which thepressures upon opposite sides of the piston are substantially balanced,it may be possible to force a downshift it the driver bears down heavily'upon the accelerator pedal to intentionally cause such a shift byovercoming the fluid pressure.

CRANKlNG ENGINE FRUM DRIVING WHEELS Since the fluid pressure suppliedfor actuating the friction clutches l5 `and i6 is derived entirely fromthe front pump in the normal operation off the transmission as thus fardescribed7 it is not possible to start the engine by pushing or towingthe vehicle without the provision of supplemental. means for directingiiuid pressure from the rear pump to the iluid pressure actuating meansfor such clutches. To provide for push-starting or tow-starting,therefore, diverting valves fidi) and 562 are arranged in the fluidconduits 12"? yand E23, respectively, as diagrammatically indicated inFig. 9, such valves being depicted as of the rotary three-way type,arranged to normally stand in the positions shown in Fig. 9 in which abranch conduit 1393 connected to the rear pump and to the bodies of thevalves 5th) and 502 is normally cut off, while direct communication isprovided from the main control valve body 2M to the clutches and theiractuating means by way of conduits lZ and E25. When the valves Sil() and502 are rotated counterclockwise, as the parts are viewed in thedrawing, however, communication between the main control valve 'andclutch actuating means is cut off. When the diverting valves are sopositioned, direct Communication is established between the rear pumpand the supply conduits leading to the clutch actuating means, by way ofconduits 139, 1392, 1393 and valves 500 and db2, as will be apparent,and upon movement of the vehicle at a speed suiiicient to developadequate pressure to engage the clutches l5 and 16, such clutches aresimultaneously engaged to provide a direct drive between the rear wheelsand the engine and thereby crank the latter.

The second speed lock-up means for preventing free wheeling in secondgear may also be controllable by means of a manually operable valve as2u?. incorporated in a branch conduit 12S connected to conduit ilZd andcommunicating with passage 53 leading to the space beneath piston 52.

While will be apparent that the preferred embodiment of the inventionherein disclosed is well calculated to fuliill the objects above stated,it will be appreciated that the invention is susceptible tomodilication, variation and change without departing from the properscope or fair meaning of the subjoined claim.

I claim:

A control system for an automatic automotive transmission of the typeincluding driving clutches and hydraulic actuating means for theclutches for selectively establishing and disestablishing different gearratios, and a reversing gear element selectively movable to and from atleast three positions including a forward driving position, a neutralposition and a reverse driving position, a control member adapted to bemounted in `a position convenient to the driver of a vehicle in whichsuch a transmission and control system are installed, said member beingbodily movable to move said reverse gear element to and from said threepositions, a valve for regulating the action of said hydraulic actuatingmeans, and a 17 supplemental actuating element for said Valve carried bysaid control member and movable independently of such bodily movement ofthe con' :fol member to cause actuation of said valve to a position tointerrupt the Huid supply to said hydraulic actuating means for theclutches, whereby by movement o said supplemental actuation element allof said clutches may be released to establish a further neutralcondition.

References Cited in the file of this patent UNITED STATES PATENTS1,256,371 Rowledge Feb. 12, 1918 1,428,221 Martino Sept. 5, 19221,619,703 Chorlton Mar. 1, 1927 2,100,810 Livermore Nov. 30, 19372,102,781 Bieretz Dec. 21, 1937 2,143,321 Kegresse Jan. 10, 19392,150,950 Thoma Mar. 21, 1939 2,151,714 Pavesi Mar. 28, 1939 2,155,198Lawrence Apr. 18, 1939 18 Kegresse June 20, Grote Aug. 15, Thompson Mar.12, Shennes June 18, Bojesen Dec. 3, Lawrence Feb. 11, Swennes Feb. 18,Lawrence May 18, Nutt et al. Oct. 26, Kelbel Aug. 20, Pollard Oct. 8,Voytech Apr. 1, Sternberg July 20, Hasbany July 25, McFarland Feb. 5,McFarland May 6, Livermore July 22,

FOREIGN PATENTS Great Britain Apr. 25,

